Thermally responsive member with longitudinally spaced contacts each actuated upon bending of the member in one direction



Seem.. E9, R67 c. 3,342,963

THERMALLY RESPONSIVE MEMBER WITH LONGITUDINALLY SPACED CONTACTS EACH ACTUATED UPON BENDING OF THE MEMBER IN ONE DIRECTION Filed March 5, 1965 yUnited States Patent O THERMALLY RESPONSIVE MEMBER WITH LON- GITUDINALLY SPACED CONTACTS EACH AC- TUATED UPON BENDING OF THE MEMBER IN ONE DIRECTION Oleg Szymber, Chicago, Ill., assignor, by mesne assignments, to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware Filed Mar. 5, 1965, Ser. No. 437,377 13 Claims. (C1. 200-122) The present invention relates to switches, and more particularly to a new and improved switch and circuit therefor for automatically recycling a load device, such as an electric motor.

For purposes of illustration, the invention will be described for use with a slide projector. However, it will be understood that the invention is not to be limited to slide projectors as the invention may be applied to other devices.

As it is known to those skilled in the art, slide projectors are usually provided with some form of slide changing device for moving a slide back Iand forth between a slide magazine and the slide projection gate of the projector. Usually, these slide changers are adapted to be manually controlled. In most present day slide projectors, means are provided for automatically reciprocating or cycling the slide carrier at repeated intervals of time selected by the operator of the device. The present invention provides a simple, inexpensive and effective means for bringing `about such an operation of a slide changing mechanism.

A primary object of the present invention is the provision of a new and improved recycling switch including a thermally responsive member associated -with iirst and second pairs of contacts, one pair of contacts being normally open and the other pair of contacts being normally close-d and associated with bi-stable means.

Another object of the present invention is the provision of a new and improved recycling switch including a bimetallic strip associated with a rrst pair of normally open contacts, a second pair of normally closed contacts, and bi-stable means, which strip has a spring value for snapping said second pair of contacts open.

LA further object of the present invention is the provision of a new and improved automatic Irecycling device including a bimetal switch, wherein the on time of the switch is independent of the total cycle time controlled by the switch.

Even another object of the present invention is the provision of a new and improved automatic recycling device including means tor varying the total time of the u cycle of operation.

These and other objects and advantages of the present invention will become apparent from the accompanying specification disclosing a preferred embodiment of the invention wherein:

FIG. 1 is a top plan view of the recycling switch of this invention;

FIG. Vla is a fragmentary plan view of the switch of FIG. l showing the normally closed contacts in their open position;

FIG. 2 is a section taken along line 2-2 of PIG. 1;

FIG. 3 is a fragmentary section taken along line 3 3 of FIG. 1; and

FIG. 4 is a diagrammatic view of the recycling switch and circuit of this invention.

Referring now to fFlGS. 1 and 2, the switch of this invention includes a generally rectangular at base 10 made of suitable dielectric material. Base 10 supports `a pin 12 .at right angles thereto, which pin pivotally mounts a generally U-shaped bracket 14. A bimetallic strip 16 is 3,342,963 Patented Sept. 19, 1967 ICC secured intermediate the ends thereof to the bight portion of bracket14 by suitable means, such as a small rivet.

As is known to -those skilled in the art, bimetallic strips used for switching are composed of two strips secured together in coextensive contact, which strips have different coefficients Vof expansion. Accordingly, when such a strip is heated it tends to warp or assume arcuate form due to the fact that one strip has a greater coefficient or expansion than the other. In the embodiment of the invention shown for illustration, bimetallic strip 16, upon being heated, warps or Iforms arcuate form so that the ends thereof move downwardly and inwardly as viewed in FIG. 1.

A suitable heater winding 18 is wound around strip 16 along the length thereof. One end of winding 18 is connected to a lug bracket 19 formed of conductive material, which bracket is `secured to base 10. The other end of winding -18 is secured to bimetal strip 16. Preferably, this end -of the heater winding is secured in an aperture in the bimetallic strip, which aperture mounts a contact Ztl.

A lug 22 is secured to base 10. This lug, which is of conductive material, mounts a contact 24. Contact 24 is adapted to be engaged by contact 20 upon heating of the bimetal strip as will be explained hereinbelow.

A contact 26 is secured to the other en-d of the bimetallic strip. This contact normally engages a contact 2=8 which is mounted on an upstanding portion at one end of a lug strip Z9. Strip 29, which is of conductive material, is suitably secured to base 10.

A -bi-stable or over-center member 30 Ialternately releasably holds contacts 26, 28 closed and opened as will be explained below. This member is of -U-shaped configuration and has one end 30a thereof received within a cut-out portion or notch of yan ear 32. This ear has an integral base 33 which is suitably secured to base 10` of the switch. The other end 30b of bi-stablemember 30 is pivotally engaged with the adjacent end of the bimetal strip. ln the embodiment of the invention illustrated, this end of the bimetal strip is shaped to form a point 16a (FIG. 2), which point is received within an aperture (not shown) in end 30b of member 30. vBi-stable member 30, which is formed of suitable spring material, tends, in its position illustrated in FIG. 1, to open up or expand thereby to hold contacts 26, 28 together. As will be explained herein, when strip 16 is heated it acts to snap contacts 26, 28 open against the relatively weak closing force of member 30 until the latter strikes an upstanding stop 34 integral with base l33 (FIG. la). When member 30 is in its FIG. 1a position, it acts to hold contacts 2,6, 28 separated in such a manner that contacts 26, 28 are permitted to close upon cooling of strip 16.

A spring strip 35 (FIGS. 1 and 3) has one end thereof secured between base 10 and lug strip 29. This spring strip is stepped upwardly as at 35a (FIG. 1,) and extends in parallel spaced relation with base 10. A contact 36 is mounted to the underside of spring strip 35. When the spring strip 35 is depressed, contact 36 engages a contact 38 which is mounted on a strip 39. Strip 39 is suitably secured to base 10. Both spring strips 35 and 39 are made of suitable conductive material.

A bracket plate 40 is secured to base plate 10 at a right angle with the latter. Bracket plate 40 mounts suitable hub means 41 which journal a shaft 42. A cam member 44 is secured to shaft 42 for rotation with the latter.

As noted in FIGS. 2 and 3, cam member 44 has an axially extending recess 45 in the outer surface thereof. When cam member 44 is in the position illustrated in FIG. 3 (which is its off position) recess 45 receives the up-turned end 35b of spring strip 35 thereby allowing the latter to assume a position wherein contacts 36 and 38 are separated. When cam member 44 is rotated E in a counterclockwise direction as indiacted in FIG. 3, the arcuate outer surface of cam member 44 engages end 35b of the spring strip and depresses the latter (to its broken line position shown in FIG. 3) for bringing about engagement of contacts 36 and 38.

As best noted in FIG. 1, cam member 44 is provided with a helical surface 47. Bimetallic strip 16 has a right angle end portion 16a which engages helical surface 47 f the cam member. Bimetallic strip 16, when not being heated, tends to assume a rectilinear configurations and thereby urges end 16a into engagement with helical surface 47. It should be apparent that rotation of cam member 44 in a clockwise direction causes contact 20 to move away from contacts 24 and that rotation of cam member 44 in a counterclockwise direction moves contact 20 toward contact 24. It will be understood that cam mem ber 44, more particularly helical surface 47 thereof, serves, among other things, as a means for setting or adjusting the spacing between contacts 20 and 24.

Cam member 44 includes an integral, arcuate flange portion 48, the ends of which flange portion are adapted to engage a protrusion 40a formed in plate 40. This protrusion acts as a stop to limit rotation of cam member 44.

Referring now to FIG. 4, t) and 51 represent low voltage lines, 28 volts for example, used in a slide projector circuit. This voltage is mentioned for purposes of illustration only and not for limiting the invention in any way as it will be appreciated that a switch constructed in accordance with the present invention can be operated by current having voltage other than the voltage mentioned. [A line 52 has one end thereof connected to line 50 at a junction 53; the other end of line 52 is connected to lug 19 of the switch. A line 54 has one end thereof connected to line 51 at a junction 55; the other end of line 54 is connected with a junction 56. A line 57 connects junction 56 with lug 39 of the switch.

A line 58 has one end thereof connected with a junction 59 and the other end thereof connected with a junction 60. A line 61 connects junction 60 with lug 22 of the switch.

Still referring to FIG. 4, 62 represents an induction type electric motor. This motor may be the driven motor of a slide changer forming a part of a slide projector. Mechanically connected to 62 is an arm 64, which arm is rotatable about a pivot 65. It will be understood that motor 62 drives arm 64 for rotation (in a clockwise direction as viewed in FIG. 4) about pivot 65. Arm 64 may form part of the drive mechanism for the slide carrier. When arm 64 is in its at rest position as illustrated in FIG. 4, the free end thereof engages a spring arm 66. Spring arm 66 supports a contact 67. A line 68 connects contact 67 with junction S6. A stationary contact 69 is mounted adjacent contact 67 and a line 70 connects contact 69 with the junction 59. When arm 64 is rotated and clears spring 66, the latter acts to close contacts 67 and 69. Arm 64 and spring 66 may be contructed as shown in the application of Karl F. Kurz, Ser. No. 188,107, led Apr. 17, 1962, now United States Patent 3,183,774.

The operation of the switch and circuit of this invention is as follows:

Assuming that the various parts are as shown in FIG. 4, when cam member 44 is rotated (in a counterclockwise direction as seen in FIG. 3) from its olf position the outer surface of member 44 engages upturned end 35b of the spring arm thereby closing contacts 36, 38. Closing of these contacts completes the circuit to heater winding 18 as follows: lines 51, 54, 57, lug strip 39, contacts 38, 36, strips 35, 29, contacts 28, 26, bimetal strip 16, heater winding 18, lug 19, and lines 52, 50. As heater winding 18 heats the bimetallic strip 16, the latter tends to assume arcuate form thereby moving contact 20 to- Ward contact 24.

As lmentioned above, when bimetal strip 16 is not heated -it tends to assume a rectilinear configuration. Ac-

cordingly, when cam 44 is rotated as viewed in FIG. 1 thereby to bend the bimetallic strip as also indicated in FIG. l, the tension in the bimetal member, or the tendency thereof to assume a straight form, acts to hold end 16a in contact with cam surface 47 and also to hold contacts 26 and 28 in engagement with each other. When strip 16 is heated to such a degree that it commences assuming a form more arcuate than its initial arcuate form illustrated in FIG. 1, the bi-stable or over-center member 30 comes into play to hold contacts 26, 28 together. It will be understood that the bimetal strip is pivotable about pin 12 and that after end 16a separates from cam surface 47, very little force need be exerted by bi-stable member 30 to hold the contacts 26 and 28 closed. As will be apparent bi-stable member 30 acts, in the position thereof illustrated in FIG. l, to prevent premature separation of contacts 26 and 28 which are in series circuit relation with heater winding 18. Premature separation of contacts 26, 28 would of course open the heater winding circuit before the strip could be heated for bringing contacts 20, 24 into engagement.

As soon as contact 20 engages contact 24 upon warping or bending of the bimetallic strip, a circuit for motor 62 is closed. This circuit is as follows: lines 51, 54, 57, lug strip 39, contacts 38 and 36, strips 35, 29, contacts 28 and 26, bimetallic strip 16, contacts 20 and 24, lug bracket 22, line 61, motor 62, line 50.

As mentioned above, arm 64 is connected with motor 62 for being driven by the latter. After motor 62 has been energized as just described, arm 64 is rotated in a clockwise direction as indicated in FIG. 4. As soon as the free end of arm 64 clears spring 66, the latter snaps contacts 67 and 69 into engagement with each other thereby to complete a circuit for motor 62 independently of the switch. This circuit for motor 62 is as follows: lines 51, 54, 68, contacts 67, 69, lines 7G, 58, motor 62, and line 50. After motor 62 has operated for a full cycle, arm 64 again returns to the position illustrated in FIG. 4 thereby opening contacts 67 and 69 for de-energizing motor 62 (contacts 20 and 24 opened before the motor cycle was completed but after contacts 67 and 69 closed).

Returning now to the switch itself, after contact 20 engages contact 24, the end of the bimetallic strip associated with contact 20 is no longer free to move by reason of the engagement between contacts 20 and 24. Therefore, as strip 16 continues to be heated and warp, the end of the strip associated with contact 26 moves thereby separating contacts 26 and 28 and snapping member 30 to its FIG. la position. Member 30 does not exert a force sufficient for preventing separation of contacts 26 and 28 by the warping action of the strip. Upon separation of contacts 26 and 28, the circuit for the heater winding is opened thereby allowing the bimetallic strip to commence cooling.

As strip 16 cools, the later tends to assume its rectilinear form. During cooling, member 30' maintains contacts 26, 28 separated thereby to prevent premature closing of the same. As soon as end 16a of the strip strikes surface 47 of the cam upon cooling of the strip, continued unbending of the bimetal strip during further cooling brings about closing of contacts 26 and 28 and snapping of member 30 to its FIG. l position thereby to energize heater winding 18 and commence another cycle of operation of the switch.

It should be apparent that the cycle of operation of the switch can be varied by changing the maximum spacing between contacts 20 and 24. This spacing is controlled or changed by rotating cam member 44 as explained above. Preferably, shaft 42, which rotates with the cam member, is associated with suitable indicia means (not shown) so that shaft 42 can be rotated to various angular positions corresponding to designated periods of time, which periods of time represent the duration of the cycle of operation of the switch.

It should be noted that the period of time that strip 16 bridges contacts 24 and 28 is completely independent of the total cycle time as controlled by cam 44. In other words, contacts 26, 28 always separate at the same length of time after contacts 20 and 24 engage each other. It will also be realized that strip 16 is constructed so that it has a spring value. By reason of this feature, when the strip warps or bends upon heating for separating contacts 26, 28, the bimetallic strip springs or snaps bi-stable member 30 from its FIG. l to its FIG. la position. On in other words, this feature provides for full and complete separation of contacts 26, 28 after they are initially separated and after the circuit to the heater winding is open.

It should also be apparent that bi-stable member 30 is so termed because it is stable in two positions, viz. the position illustrated in FIG. l and the position illustrated in FIG. 1w. Actually, the member 30 acts as an overcenter member for alternately releasably holding contacts 26, 28 closed and opened.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not to be so limited. On the contrary, the invention is susceptible of various forms and modications without departing from the spirit and scope of the appended claims.

l claim:

1. A recycling switch comprising a base, a thermally responsive strip, support means engaging such strip at one portion along the length thereof and mounting the same on said base so that the remaining portion of the strip is free for warping upon being heated, a first pair of normally open contacts including one contact mounted on the base and the other contact mounted on the strip in spaced relation from said one portion for movement toward and away from said one contact upon heating and cooling of the strip, respectively, stop means on the base for arresting movement of said other contact away from said one contact, a second pair of normally closed contacts including one contact mounted on the base and the other contact mounted on the strip in spaced relation from said one portion and said one contact of said second pair of contacts for movement toward and away from the latter upon cooling and heating of the strip, respectively, bi-stable means connected with said strip adjacent said second pair of contacts for alternately releasably holding the latter open and closed, electric heating means disposed in thermal conductive juxtaposition to said strip in series with said second pair of contacts for heating said strip, said strip being mounted so that upon being heated it warps in a direction causing closing of said first pair of contacts thereby preventing further movement of the portion of the strip adjacent said other contact of the rst pair of contacts, said strip being capable upon continued heating to overcome the force of said bi-stable means and thereby open said second pair of contacts, said bi-stable means being capable of developing a sufficient force on said strip to hold said second pair of contacts open until movement of said strip in the other direction upon cooling results in arresting further movement of said strip portion by said means whereupon continued movement of the strip in said other direction develops a force sucient to overcome the vforce of said bi-stable means and thereby close said second pair of contacts for commencing another cycle of operation.

2. The switch according to claim 1 wherein said strip includes a bimetal member having a spring value for snapping said second pair of contacts open.

3. A recycling switch comprising, a base, a thermally responsive strip pivotally mounted on said base adjacent one portion of the former and adapted, upon being heated, to Warp in one direction for assuming arcuate form, a rst pair of normally open contacts including one contact mounted on the base and the other contact mounted on the strip in spaced relation from said one portion for movement toward and away from said one contact upon heating and cooling of the strip, respectively, stop means on the base for arresting movement of said other contact away from said one contact, a second pair of normally closed contacts including one contact mounted on the base and the other contact mounted on the strip in spaced relation from said one portion and said one contact of said second pair of contacts for movement toward and away from the latter upon cooling and heating of the strip, respectively, bi-stable means associated with said strip adjacent said second pair of contacts for alternately releasably lholding the latter open and closed, electric heating means disposed in thermal conductive juxtaposition to said strip in series with said second pair of contacts for heating said strip, said strip being arranged so that warping thereof in said one direction causes closing of said irst pair of contacts thereby preventing further movement of the portion of said strip adjacent said other contact of the first pair of contacts, said strip being capable upon continued movement in said one direction to overcome the force of said bi-stable means and thereby open said second pair of contacts, lsaid bi-stable means being capable of developing a suicient force on said strip to hold said second pair of contacts open until movement of said strip in the other direction upon cooling results in arresting further movement of said strip portion by said stop means whereupon continued movement of the strip in said other direction develops a force suilcient to overcome the force of said bi-stable means and thereby close said second pair of contacts for commencing another cycle of operation.

4. The switch according to claim 3 wherein said strip includes a bimetal member having a spring value for causing full opening of said second pair of contacts after initial opening ofthe same.

5. The switch according to claim 3` wherein said stop means are adjustable for varying the intervals of time between opening and closing of said first pair of contacts.

6. An automatic recycling device comprising, a thermally responsive member, a first pair of normally open contacts with one contact being xed and the other contact being mounted on said member for movement toward said one contact upon heating of said member and for movement away from said one contact upon cooling of said member, stop means for stopping movement of said other contact away from said one contact, a second pair of normally closed contacts with one contact thereof being tixed and the other contact being mounted on said member, bi-stable means for alternately releasably holding said second pair of contacts closed and opened, said member being mounted so that upon being heated said first pair of contacts are closed and said second pair of contacts are then opened and so that upon being cooled said rst pair of contacts open followed by closing of said second pair of contacts, electric heating means in thermal conductive juxtaposition with said member, said heating means having two terminals with one terminal connected to said member and the other terminal connected to one of a pair of line terminals, a load device with one terminal thereof connected to said one contact of said first pair of contacts and with the other terminal connected to said one line terminal, said one contact of said second pair of contacts being connected to the other line terminal.

7. The device according to claim 6 further delined by a connection between said one load terminal and said other line terminal, a normally open switch in said connection, means operated by the load device for closing said switch after said load device has been energized and for maintaining said switch closed for a motor operating cycle.

8. The device according to claim 6 wherein said thermally responsive member comprises a bimetal strip.

9. The device according to claim 6 wherein said stop means is adjustable for varying a cycle of operation of the recycling device.

10. An automatic recycling device comprising, a rst pair of normally lopen contacts and a second pair of normally closed contacts, means including an elongated, thermally responsive member supported at one portion thereof and having the remaining portion thereof free to bend upon heating and cooling, said member supporting one contact of each of said pairs of contacts in spaced relation along the length of the former, base means fixedly supporting the other contact of cach of said pairs of contacts in spaced relation longitudinally of said member, biasing means yieldably holding said second pair of contacts closed, said member being adapted, upon being heated, to bend in one direction thereby to close said first pair of contacts whereupon movement of said member at the portion thereof adjacent said rst contacts is stopped so that continued bending of said member in said one direction subsequently causes opening of said second pair of contacts, said member also being adapted, upon being cooled, to bend in the other direction thereby to open said rst pair of contacts and thereafter to close said second pair of contacts, electric heating means in thermal conductive juxtaposition with said thermally responsive means, said heating means being in series With said second pair of contacts, said rst pair of contacts being in series with said thermally responsive means and a terminal for connection with a load device.

11. The device according t claim 10 wherein said biasing means comprising bi-stable means for alternately releasably holding said second pair of contacts closed and opened.

References Cited UNITED STATES PATENTS 2,309,193 1/1943 Holmes 200-139 2,374,097 4/ 1945 Holmes 200-139 2,403,798 7/1946 Holmes 200-139 2,798,131 7/ 1957 Collier 200-122 1,957,088 5/1934 Vischer et al 200--122 2,045,821 6/1936 Auston 200--122 2,347,514 4/ 1944 Shively et al 20G-122 2,871,315 1/1959 Dales 200138 2,673,269 3/1954 Hobbs 200-67 X 2,825,785 2/1950 Taylor 200-138 X BERNARD A. GILHEANY, Primary Examiner.

T. D. MACBLAIN, H. A. LEWITTER,

Assistant Examiners. 

10. AN AUTOMATIC RECYCLING DEVICE COMPRISING, A FIRST PAIR OF NORMALLY OPEN CONTACTS AND A SECOND PAIR OF NORMALLY CLOSED CONTACTS, MEANS INCLUDING AN ELONGATED, THERMALLY RESPONSIVE MEMBER SUPPORTED AT ONE PORTION THEREOF AND HAVING THE REMAINING PORTION THEREOF FREE TO BEND UPON HEATING AND COOLING, SAID MEMBER SUPPORTING ONE CONTACT OF EACH OF SAID PAIRS OF CONTACTS IN SPACED RELATION ALONG THE LENGTH OF THE FORMER, BASE MEANS FIXEDLY SUPPORTING THE OTHER CONTACT OF EACH OF SAID PAIRS OF CONTACTS IN SPACED RELATION LONGITUDINALLY OF SAID MEMBER, BIASING MEANS YIELDABLY HOLDING SAID SECOND PAIR OF CONTACTS CLOSED, SAID MEMBER BEING ADAPTED, UPON BEING HEATED, TO BEND IN ONE DIRECTION THEREBY TO CLOSE SAID FIRST PAIR OF CONTACTS WHEREUPON MOVEMENT OF SAID MEMBER AT THE PORTION THEREOF ADJACENT SAID FIRST CONTACTS IS STOPPED SO THAT CONTINUED BENDING OF SAID MEMBER IN SAID ONE DIRECTION SUBSEQUENTLY CAUSES OPENING OF SAID SECOND PAIR OF CONTACTS, SAID MEMBER ALSO BEING ADAPTED 